<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
</head>
<link rel="stylesheet" href="css/index.css">
<body>
<div class="con">
    <div class="bn">上面</div>
    <div class="bn">中间</div>
    <div class="bn">下面</div>
</div>
</body>
</html>